1. Field of the Invention
The present invention relates to a method for determining an angle of rotation.
2. Description of the Background Art
WO 96/16316, which corresponds to U.S. Pat. No. 5,880,586, discloses a method for determining an angle of rotation of a rotation axis, whereby a permanent magnet is arranged rotationally symmetric on a front of a rotation axis. To perform a contactless determination of the angle of rotation of the rotation axis, the rotating magnetic field is measured by means of two Hall sensors. The two Hall sensors are integrated into the same silicon chip and formed orthogonal to one another, i.e., at an angle of 90°, and arranged or oriented directly opposite the front of the rotation axis in such a way that one of two Hall sensors generates a signal according to the relation Uh1=C1*I*B*sin(α) and the other sensor of the two Hall sensors a signal according to the relation Uh2=C1*I*B*cos(α). With the assumption that the material constants C1 and C2 are more or less the same and the operating current is the same and the magnetic field components are the same, the absolute angle of rotation α can be determined from the relation α=arctan (Uh1/Uh2).
EP 2 117 103 B1, which corresponds to US 20090278531, and which is incorporated herein by reference, discloses an arrangement of two Hall sensors, formed orthogonal to one another, for controlling an electric motor, whereby the integrated circuit has adjustable compensation means. The sensitivity of the Hall sensors and the offsets of the measurement signals of both Hall sensors are set with the compensation means. Furthermore, EP 2 354 769 A1, which corresponds to US 20110187351, and which is incorporated herein by reference, discloses an arrangement of three Hall sensors integrated into the same silicon chip and arranged orthogonal to one another. A time-consuming positioning of the sensor arrangement, i.e., a reduction of the incorrect adjustment of the three Hall sensors relative to the rotation axis, is performed by means of the measurement signal of the third magnetic field sensor to reduce an angle-dependent offset due to the incorrect adjustment on the order of 1°.
Furthermore, an arrangement of two orthogonally arranged Hall sensors within an integrated circuit is also known from the data sheet MLX90316, whereby two such integrated circuits, also called “dies,” are arranged in the same plane in immediate proximity to one another on the same carrier and in the same circuit housing. This type of carrier is also called a lead frame. A first angle of rotation is calculated with the first of two Hall sensors of the first die and a second angle of rotation, shifted by 180° versus the first angle of rotation, is calculated with the second of the two Hall sensors of the second die in each case according to the aforementioned arctan function. The values for calculating the arctan function are stored in a memory.